Prices rise, salaries go up, website traffic grows. Whenever something changes, we describe it as a percentage — and getting that number right matters. Here's how percentage increase works.
The percentage increase formula
Percentage increase = (new value − old value) ÷ old value × 100
Traffic grew from 4,000 to 5,000 visits a month:
(5,000 − 4,000) ÷ 4,000 × 100 = 25% increase.
Three steps: find the difference, divide by the starting value, multiply by 100. The starting value is always the number you divide by.
How to increase a number by a percentage
To add a percentage to a number, multiply by (1 + percentage ÷ 100).
A $200 rent rising 15%: 200 × 1.15 = $230.
You can also calculate the increase on its own (200 × 0.15 = $30) and add it to the original.
Worked examples
- Salary: $3,000 → $3,300. Increase = 300 ÷ 3,000 = 10%.
- Price: a $12 item goes up by 8%. 12 × 1.08 = $12.96.
- Population: 80,000 → 92,000. Increase = 12,000 ÷ 80,000 = 15%.
Why up 50% then down 50% doesn't get you back
Start with 100 and add 50%: you have 150. Now take away 50%: you have 75. The decrease is applied to a larger number, so you end up below where you began. To reverse a 50% increase, you need a 33.3% decrease.
This is why percentage changes can't simply be added or subtracted from each other, and why "recovering" a loss takes a bigger percentage than the loss itself.
Percentage increase vs percentage points
If an interest rate goes from 4% to 5%, that's a rise of one percentage point but a 25% increase in the rate itself (1 ÷ 4). Headlines mix these up constantly, so it pays to check which one is meant.
Calculate it instantly
The Percentage Increase Calculator does both jobs: add a percentage to a number, or find the percentage increase between two numbers. It also warns you if the change is actually a decrease.
Common mistakes
- Dividing by the new value instead of the old one.
- Starting from zero. A change from 0 can't be expressed as a percentage — it's undefined.
- Adding percentage changes together across several periods. Multiply the growth factors instead.
FAQ
Can a percentage increase be more than 100%? Yes. Going from 50 to 150 is a 200% increase — the value tripled.
How do I calculate an increase over several years? Multiply the yearly growth factors. 10% then 20% growth is 1.10 × 1.20 = 1.32, a 32% total increase.
How do I find the original number before the increase? Divide the new value by (1 + percentage ÷ 100). If something is $230 after a 15% rise, the original was 230 ÷ 1.15 = $200.
Try it now
Use the free Percentage Increase Calculator for a quick answer.
Related reading
See How to Calculate Percentage Decrease for the opposite direction, or start with How to Calculate a Percentage. Browse the full blog for more guides.